AB1521 IgG4-RD AND SLE: COEXISTENCE IN THE KIDNEYS
Authors: O. Mena Mirands, C. Chao, M. Vukelic
Journal: Annals of the Rheumatic Diseases (2022)

Background IgG4 related disease (IgG4-RD) is an immune-mediated fibro-inflammatory condition that can mimic malignant, infectious and inflammatory diseases (1). Systemic lupus erythematosus (SLE) is a chronic autoimmune condition characterized by multisystem inflammation and autoantibody generation (2). Overlap of IgG4-RD and SLE is not frequent, however there have been few cases reported with kidney involvement secondary to both conditions (2,3). We present a case of an elderly male with a new diagnosis of IgG4-RD and SLE with kidney involvement. Objectives To present a case with a new concomitant diagnosis of IgG4-RD and SLE. Methods Case report. Results A 67-year-old man with longstanding history of cervical lymphadenopathy (LAD) presented to the Rheumatology Clinic due to intermittent lower extremity rash, anemia, worsening fatigue for the past 2 years. Prior history includes controlled DM type 2 and HTN treated with amlodipine. Denied photosensitivity, oral ulcers, sicca symptoms, Raynaud’s phenomenon, weight loss, fever, chills, joint pain. Physical examination revealed bilateral cervical LAD and a non-blanching purpuric rash on lower extremities consistent with leukocytoclastic vasculitis, later confirmed with biopsy. Further workup revealed, normocytic anemia (Hgb 9.9 mg/dl), positive ANA (&gt;1:2560, homogeneous pattern), positive dsDNA (211 IU/ml), positive histone Ab (413 IU/ml), low C3 (28 mg/dl), low C4 (1 mg/dl), increased IgG4 level (2787 mg/dl) and proteinuria 1100 mg/g with microalbuminuria, no urine casts. ANCA serologies were negative. Pan-CT showed mild cervical, retroperitoneal, pelvic LAD bilaterally. Kidney biopsy was performed and revealed severe diffuse tubulointerstitial nephritis, plasma cell rich (more than 40 IgG4 + cells seen per 40X hpf), with moderate to severe chronicity in addition to diffuse mesangial IgG and IgM staining with focal tubular basement membrane IgG and C1 staining consistent with mesangial proliferative class II lupus nephritis. Patient was started on moderate dose steroids (due to DM), hydroxychloroquine and azathioprine with resolution of LCV rash, anemia, LAD, improvement in dsDNA, proteinuria, complement levels. Conclusion SLE and IgG4-RDs are autoimmune diseases that cause damage to several organs, including lymph nodes and kidneys. Both are associated with hypocomplementemia and involvement of autoantibody-producing B cells and plasma cells. Patients with SLE present with positive antibodies such as anti-dsDNA and anti-Sm antibodies. On the other hand, IgG4-RD lack a specific antibody and the IgG4 is thought to be the result of the pathogenic process and not pathogenic by itself (1,2). Histologically, SLE presents with inflammatory cell infiltration in organs, whereas IgG4-RD is associated with fibrosis and organ enlargement (1-3). Lupus nephritis causes wide spectrum renal involvement whereas IgG4-RD most common presentation is tubulointerstitial nephritis (TIN), although other glomerular lesions, such as membranous nephropathy, have been reported (1-2). Our patient presented with proteinuria, positive antibodies for SLE, low complements and high levels of IgG4 which makes us consider that both diseases were active at time of diagnosis. This was confirmed by renal biopsy showing chronicity of IgG4-RD and lupus nephritis as a consenquence of progression of autoimmunity. The treatment of both conditions is immunosupression with medium to high doses of steroids and a steroid sparing agent. Due to patient preference he was started on azatioprine along with medium dose steroids with adequate clinical response. This case highlights the fact that SLE and IgG4-RD can coexist and it should be supected in elderly patients with lympadenopathy and renal disease. References [1]Kamisawa T, et. al. IgG4-related disease. Lancet. 2015;385(9976):1460-1471. [2]Zaarour M, et.al. An Overlapping Case of Lupus Nephritis and IgG4-Related Kidney Disease. J Clin Med Res. 2015;7(7):575-581. [3]Naramala S, et al. An Overlapping Case of IgG4-Related Disease and Systemic Lupus Erythematosus. J Investig Med High Impact Case Rep. 2019;7:1-4 Disclosure of Interests None declared